Improvement in diamond millstone-dressing machines



F. S. DAVENPORT.

Diamond MillstoneDressing-Machines.

No, 142,153. Patented August26.1873.

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rnnnnnrc s. DAVENPORT, or JERSEYVILLE, ILLlNOIS.

IMPROVEMENT IN DIAMOND MlLLSTONE-DRESSING MACHINES.

Specification forming part of Letters Patent No. 142,153, dated August 26, 1873 application filed May 21, 1873.

To all whom it may concern:

Be it known that I, FREDERIO S. DAVEN- PORT, of J erseyville, in the county of Jersey and State of Illinois, have invented a new and Improved Diamond Millstone-Dressing Machine and I do hereby declare that the following is a full and exact description of the same, reference being had to the accompanying drawings and to the letters of reference marked thereon.

This invention relates to an improvement in diamond millstone-dressin g machines, and has reference to that class of machines which produce their effect by drawing the diamond over the face of the stone, and differs from other machines of its class in being capable of adj ustment, so as to make the dress'cuts converge as they approach the eye of the stone, or diverge, if so required, and the degree of convergence or divergence varied at the will of the operator. The in vention further relates to certain improvements in the construction of the sliding block which carries the diamond, whereby the latter is manipulated with unusual ease and certainty, as will be seen by inspection of the drawing.

In the drawings, Figure 1 is a plan view of the machine. Fig. 2 is a side elevation. Fig. 3 is a front elevation.

A, Fig. 1, represents a foundation or bed plate, preferably made of cast-iron, designed On the upper side of this bed-plate is a sliding plate, B, provided with a guide-slot, b. To the rear of this plate is pivoted or hinged, at the point e, a flat bar, 0, provided with a guide-slot, b, similar to the slot in plate B. Into these slots, the inner sides of which are slightly inclined toward each other at the bottom side, are fitted guide-blocks t t, pivoted to the bedplate by studs a n. D represents a plate secured to the rear of the plate B, and is provided, near its outer extremity, with a circular slot, in which plays a tightening-screw, 1. Thus are the parts B and U pivoted together, and can be secured at any required horizontal angle to each other by the tightening-screw r. B, Fig. 2, is atube which revolves upon the projecting upper end of the stud a. To the upper extremity of this tube is secured a handwheel, a, and at the lowerextremity a pinion, which engages with a rack, 9. Just above this pinion is a wheel, m, furnished upon its periphery with teeth or notches, which are acted upon by a check-spring, l, secured to the guide-block t. The front edge of plate B is provided with a V-shaped horizontal guidebar, E, just to the rear of which is a rib, is, extending the entire length of the guide-bar, and downward so as to rest slightly upon the face of the stone. The guide-bar E is provided witha sliding block, T, to which is pivoted, at the point Y, the diamond-holder, furnished with a handle, G, the diamond being secured in the holder by the ordinary means. 0 represents a set-screw in the top of the block T. Upon thehead of this set-screw rests the projecting shoulder Q of the diamond-h0lder.

The operation of the machine isas follows When it is desired to make the dress-cuts upon the face of the stone parallel to each other, the two slots b b are set in a straight line, and secured in that position by the tightening-screw r. The bed-plate being laid upon the face of the stone, and the machine brought into position so that the guide-bar E ranges I properly with the dress-lines, the sliding block T is brought to the skirt of the stone, which would be at about the point L. The diamond now requires adjusting, so as to makethe cut deep or sh.llow, as may be required. This adjustment is effected quickly and to the greatest nicety by the set-screw O, a slight" turn of which, acting upon the shoulder Q, raises or depresses the heel of the diamondholder, and consequently governs the depthof the dress-cut. The operator now takes the handle G firmly in his hand, and, keeping the shoulder Q well down upon the head of the setscrew 0, pushes the sliding block T steadily to the opposite end of the guide-bar E, on reaching which the handle is tilted slightly forward, as indicated by the arrow, Fig. 3, so as to raise the diamond from the face of the stone, and thus raised it is brought back to its former position.

In order to bring the diamond into position for the next cut, the hand-wheel at is turned until the vibrating end of the check-spring Z slips into the next notch on the periphery of the wheel upon which it acts. The preceding operation, already described, is then repeated. I

When it is desired to make the cuts wider apart or closer together, the wheel on is provided with a greater or less number of teeth or notches. But practice and experience show that it is generally preferable, for reasons that will presently be given, that the dress-cuts should not be parallel, but that they should converge as they approach the eye of the stone; and, further, that no fixed degree of convergence will answer, as some stones are more open or porous toward the eye than near the skirt, and some the reverse. Stones are also frequently found to be harder on one side of the face than on the other. It therefore follows that some means for not only causing the dress-cuts to converge at particular parts of the stone, but to govern the degree of convergence, is eminently desirable, and to the accomplishment of that end this machine is well adapted.

To elucidate this matter more fully it may be observed that, aside from the fact that the generality of millstones do not wear uniformly for the reasons cited, the wear is always much greater at the skirt than at the eye in consequence of the speed increasing as the distance from the eye. Now, by reducing the distance between the dress-cuts as they approach the eye of the stone, it follows that the wearingsurface may be reduced in the same ratio as the speed ,and consequently a dress imparted to the stone that will'cause it to wear nearly to a perfect plane.

The very simple means by which the dresscuts are made to converge will be readily understood by considering the center lines of the slots 12 b as the sides of a triangle of which the base is a straight line drawn from the center of the stud n to the center of the stud n. Then, in accordance with a wellknown geometrical principle, the path of the vertex of the triangle will be a circular arc, and consequently the dress-cuts will converge as the radiuses of that are.

What we claim as our invention in this machine, and desire to secure by Letters Patent, 1s

1. The sliding plate B and sliding bar 0,

provided with the guiding-slots b b, the said parts being hinged or pivoted together for united operation, substantially as and for the purpose specified.

'2. The diamond-holder F, pivoted to the sliding block T, in combination with the adjusting-screw O.

3. The diamond millstone-dressing machine producing the curvilinear motion described by means of two straight guide-slots made so as to admit of horizontal angular adjustment to each other, for the purpose specified, the said guide-slots being arranged either in the sliding parts B and (J or in the bed-plate A.

This specification signed and witnessed this 15th day of May, 1873.

FREDERIU S. DAVENPORT.

Witnesses:

WM. H. SOHROEDER, WILLIAM H. SronoKEL. 

